Dental radiography is the single most frequent type of diagnostic x-ray examination. A significant reduction in the radiation dose to the population can be achieved by using the fastest film available that is compatible with the diagnostic task. In 1981 a new dental x-ray film was introduced which offered the prospect of reducing patient exposure by approximately 50 percent while maintaining the diagnostic yield as compared to the standard film. The specific aim of this study is to evaluate the performance of the new film by comparing the diagnostic yield of the faster dose-sparing film with the standard film under various clinical conditions. This will be accomplished by using geometrically identical matched-paired sets of radiographs (new film-standard film) obtained at high and low kVp settings. Proximal surface carious lesions will be the test item for the evaluation process. The sample set will be evaluated by a panel of dentist clinicians. The films will be presented in a randomized and blinded manner in single film mounts and each evaluator will record his or her findings in a standardized format. Optimization of the film reading process will include reduced ambient lighting, masked viewbox to reduce glare and short film reading sessions to minimize fatigue. The data will be entered and transfered to a computer file. Standard statistical software packages will be used to perform multivariate and univariate analyses which will be used to assess film speed, exposure, interpretor and processing differences as well as interactions. This will provide a quantitative means of comparing the diagnostic yield of the two films. If the films are equivalent, then the use of the new faster film will reduce the radiation dose of the population from dental radiography about 50 percent.